Various different hanging cradle constructions of this kind are known to the art, wherein said cradles are constructed to work with a single line means which is intended to pass through a guide mounted on the upper free part of a centrally located arm or post.
Hanging cradles of this kind are often used for working on the external wall surfaces of building structures, and when the cradle is used for this purpose the uppermost part of the line is attached to a holder located adjacent to the roof of the building and the cradle can be raised and lowered along the line, with the aid of a machine intended herefor.
It is also known that such hanging cradles are encumbered with a technical problem, in that the supporting surface or platform of the cradle, which platform is normally horizontal in use, will tip or tilt as soon as the gravitational centre of the cradle and the load carried thereby is shifted to one side of the line.
This shifting of the gravitational centre will take place, for instance, when a person carried by the cradle moves along the platform, from the central region of the cradle to the end or edge regions thereof.
It is also known that tilting of the cradle as a result of a shift in the gravitational centre can be counteracted to some extent by giving the post a considerable length vertically away from the platform, while still allowing the line guide to be placed on the upper free part of the post.
Unfortunately, this solution prevents work from being carried out by a person standing on the platform adjacent to the attachment point and slightly therebeneath, when the cradle is raised to its highest raisable position.
One example of the present state of this art is found described and illustrated in U.S. patent specifications Nos. 3 967 696 and 3 630 315.
It has also been proposed to enable the distance between the working platform and the free part of the post to be decreased when said free post part is in co-action with the attachment. A facility is also provided whereby the cradle can be raised further, for the purpose of reducing the tendency of the cradle to tilt in response to a lateral shift in the centre of gravity.